This invention relates to electrosurgical apparatus and in particular to such apparatus for performing laparoscopic, pelvoscopic, arthroscopic, thoroscopic and the like surgical procedures. Procedures of the foregoing type are experiencing explosive growth in that incisions are kept to a minimum size and thus such procedures facilitate shorter hospital stays and lower costs. For example, with laparoscopic surgery, a patient can return to, normal activity within about one week, whereas with procedures where a large incision is made, about a month for full recovery may be required. It is to be understood that hereinafter and in the claims, whenever the term xe2x80x9claparoscopicxe2x80x9d is employed, similar procedures such as pelvoscopic, arthroscopic, thoroscopic, and the like where small incisions of the foregoing type are made are also encompassed by this term.
Prior art electrosurgical laparoscopic apparatus typically include an active electrode probe that is removably insertable through a trocar sheath and that includes an electrode having an insulative coating thereon. The tip of the probe may be of different conventional shapes such as needle-shape, hook-shape, spatula-shape, graspers, scissors, etc. and serve various conventional functions such as suction, coagulation, irrigation, pressurized gas, cutting, etc. There are, however, various problems which may arise with respect to the use of such a prior art apparatus when used in laparoscopic or like procedures.
A first problem may arise if the insulation on the active electrode is damaged thereby allowing active current (possibly in the form of arcing) to pass therethrough directly to the patient""s tissue (possibly the bowel or colon) whereby peritonitis may set in within several days. A second problem which can arise with prior art apparatus is caused by a capacitive effect where one electrode of the capacitance is the active electrode and the other electrode of the capacitance is a metallic trocar sheath and the dielectric between these elements is the insulation on the active electrode. Current from the active electrode will be capacitively coupled to the trocar sheath and then returned through the body and the return electrode to the generator. If this current becomes concentrated, for example, between the trocar sheath and an organ such as the bowel, the capacitive current can cause a burn to the organ. A third potential problem occurs if the active electrode contacts another instrument within the peritoneal cavity such as metallic graspers or the like. The above-mentioned capacitive effect also arises in this situation where the first electrode is the active electrode and the second electrode is the metallic graspers or the like. Thus, where the grippers contact a unintended site, injury may occur.
To solve some of the above identified problems, an electrosurgical apparatus as disclosed in U.S. Pat. No. 5,312,401 to Newton et al. and assigned to the assignee of the present invention has been proposed, the contents of which are incorporated herein by reference. Newton et al. disclose an electrosurgical apparatus that includes a safety shield that surrounds an active electrode and that includes insulation provided at least on the outer surface of the shield and preferably also provided on the inner surface of the shield. The safety shield is connected to a return lead via a low impedance path that includes monitoring circuitry used to detect the shield current and determine an abnormal condition therefrom.
In the event that the insulation on the active electrode is damaged, current will pass through the damaged insulation to the shield and then be returned to the return lead via the low impedance electrical connection between the shield and the return lead of the electrosurgical generator. A monitor circuit responsive to the shield current deactivates the electrosurgical generator whenever the shield current corresponds to an abnormal condition such as an insulation breakdown. The insulated shield of Newton et al. also addresses the second and third above-mentioned problems by harmlessly returning any current which is capacitively coupled to the shield to the return lead via the above-mentioned low impedance connection.
Referring to FIG. 1 a cross-sectional view of an illustrative laparoscopic apparatus in accordance with Newton et al. is shown. A tubular safety shield assembly 15 includes a tubular shield 9 having a layer of insulation 11 provided on the outer surface thereof and an optional layer of insulation 13 provided on the inner surface thereof. The tubular shield assembly is inserted through trocar sheath 1 to thereby provide a passageway through which the active electrode probe 3 may be inserted. An elongated port 23 may extend through the active electrode through which irrigation fluids, suction, a pressurized gas stream, etc. may pass. When active probe 3 and tubular shield assembly 15 are in their respective inserted positions as shown in FIG. 1, the shield 9 surrounds the active probe from at least (a) a proximal point 17 prior to the entry point 19 of the active probe into the trocar sheath 1 to (b) a distal point 21 in proximity to the tip 7 of the active probe. Shield monitor circuitry 25 is connected to shield 9 via a dual conductor lead 27 whereby the integrity of the connection of the shield to the monitor circuitry can be monitored.
The active electrode probe 3 is connected to an electrosurgical generator 31 which may be of a conventional type via an active lead 35. The electrosurgical generator is connected to a patient return electrode 37, preferably of the dual area type, via the shield monitor circuitry 25 and, in particular, the return terminal of the generator is connected to circuitry 25 via lead 29 while the circuitry 25 is connected to the return electrode via lead 33. Upon detection of a fault condition by the shield monitor circuitry, the electrosurgical generator 31 may be deactivated by opening a relay in the connection between the generator and patient return electrode 37 although other means may also be employed to deactivate the generator.
Referring to FIG. 2 a generalized block diagram of the shield monitor circuitry 25 shown in FIG. 1 and used in Newton et al. is shown. A conductivity monitor 39 is connected to dual lead 27, the purpose of the conductivity monitor circuit being to measure the integrity of the connection of lead 27 to shield 9. The dual connection provides a redundant path for shield monitoring current which is applied to lead 27 as will be described in more detail hereinafter with respect to FIG. 9. A shield current sensor 41 senses the current passing from the shield 9 to return electrode lead 29, 33 and may provide a signal voltage proportional to the instantaneous value of the shield current.
Measurement electronics circuitry 43 includes various circuits for measuring different parameters of at least the sensed shield current. The first of these circuits is a full bandwidth amplitude sensor circuit 47 which measures the amplitude of the full bandwidth of the sensed shield current. Processing and decision circuitry 53 determines whether this amplitude exceeds a predetermined threshold and, if it does, a fault condition may be applied to indicators 61 over line 55. Indicators 61 may be aural and/or visible and provide an appropriate alert. A data logger 73 may also be connected to processing and decision circuitry 53 to provide a hard copy of various safety conditions.
In addition to applying an alert signal over line 55, a generator deactivate signal is applied over line 69 to a relay 71 which opens the connection between return electrode 37 and generator 31 to thus deactivate the generator and discontinue the application of electrosurgical energy. That is, the monitor circuitry 25, when used outside host electrosurgical generator 31, is preferably used with an electrosurgical generator of the type having a dual return electrode lead whereby the integrity of the return electrode connection can be monitored. Such monitoring circuitry is known whereby a split (or double) patient electrode is employed and a DC current (see German Patent No. 1139927 published Nov. 22, 1962) or an AC current (see U.S. Pat. Nos. 3,933,157 and 4,200,104) is passed between the split electrodes to sense patient contact resistance or impedance between the patient and the electrodes. If an open circuit condition is sensed, the generator is deactivated. Since the relay 71 of FIG. 2 is opened upon detection of a fault condition, the return electrode connection is also opened to thus deactivate the generator. However, it is to be understood other means will also occur to those skilled in this art for deactivating the generator upon detection of a fault condition by monitor circuitry 25.
Relative amplitude measurement circuitry 51 may be responsive to the ratio of the amplitudes of the sensed shield current and the sensed return electrode current as determined by return current sensor 65. Processing and decision circuitry 53 determines whether this ratio exceeds a predetermined threshold and if it does an alert signal is applied over line 55 while a deactivate signal is applied over line 69 to relay 71 in a manner similar to that described above with respect to the absolute amplitude fault condition.
Phase sensing circuitry 75 is responsive to the phase difference between the voltage applied to the active lead 35 of FIG. 1 and the sensed shield current. In FIG. 1 the monitor circuitry 25 is indicated as being housed outside host electrosurgical generator 31. However, it may also be incorporated within the electrosurgical generator. In the latter instance, access may be readily gained to the active voltage and thus the phase comparison made by phase sensing circuitry 75 can be readily effected. When the monitor is located outside of the host electrosurgical unit, it is somewhat more inconvenient to gain access to the applied voltage signal; nonetheless, appropriate means will occur to those of ordinary skill in the art to gain access to this signal.
Detection of the phase difference between the active voltage and the shield current is a particularly good indicator of a fault condition. That is, normal shield currents are exclusively capacitivexe2x80x94in particular, due to the capacitive coupling between active electrode 5 and shield 9, there is a 90xc2x0 phase difference between the active voltage and the shield current under normal conditions. Hence, as long as the insulation between the active electrode and the shield is intact, a normal condition will be sensed by phase sensing circuitry 75.
In general, the phase sensing circuitry, in response to the phase difference between the applied inputs being 90xc2x0, provides a first output (high voltage, for example). If there is an insulation breakdown between the active electrode 5 and the safety shield 9, arcing will typically occur and such arcing currents are almost exclusively in phase with the applied voltage. That is, the shield current will be in phase with the active voltage. Phase sensing circuitry 75 detects this in phase, fault condition to change the output from high to low.
Spectral sensing or filtered bandwidth circuitry 77 provides a further reliable means for detecting the presence of arcing between the active electrode and shield. Moreover, this method does not need access to the active electrode voltage and thus readily lends itself to those monitor circuitry 25 which are located outside the host electrosurgical generator 31. Spectral sensing circuitry is responsive to at least one predetermined bandwidth of the sensed shield current to detect the presence of a shield current produced by arcing where the arcing will typically occur between the active electrode and the shield due to insulation breakdown therebetween.
Both the phase sensing circuitry 75 and the spectral sensing circuitry 77 also apply inputs to processing and decision circuitry 53 in a manner similar to that described above with respect to circuits 47 and 51 whereby the outputs of circuitry 75 and 77 may be utilized to actuate indicators 61 and data logger 73 and deactivate the electrosurgical generator via relay 71. As indicated above, one or more of the sensing circuits 47, 51, 75, and 77 may be independently utilized or utilized in combination to effect the shield monitor function of circuitry 25.
Various measures have been taken in Newton et al. to render the operation thereof fail-safe. For example, if the monitor circuitry 25 is employed outside host electrical generator 31, there is a possibility the user may connect the return electrode directly into the electrosurgical generator rather than through the monitor circuitry 25 as illustrated in FIG. 1. If this occurs, the shield will not be connected to the return electrode lead through a low impedance path, as will be discussed below, and thus monitor circuitry 25 will be inhibited from performing its monitoring function. To provide an alert to the user that the return electrode has been inappropriately directly connected to the generator 31, a shield to ground voltage sensor 49 may be provided, the sensor 49 being responsive to the shield voltage over line 45 via lead 27. The output of shield/ground voltage sensor 49 is applied to processing and decision circuitry 53 where an appropriate indicator 61 is actuated if the return electrode is directly connected to the electrosurgical generator.
If the return electrode is directly connected to the electrosurgical generator, the voltage on the shield will rise to a substantial percentage of the active voltage in view of an open circuit between the shield and the return electrode lead. Hence, whenever the voltage on the shield exceeds a predetermined threshold, an appropriate signal is applied to processing and decision circuitry 53 over line 57 to thereby provide a desired alert.
Furthermore, when the monitor circuitry 25 is provided outside host electrical generator 31, it is desirable in some instances to battery power the monitor circuitry 25. That is, if the monitor circuitry is powered from an operating room electrical outlet, this will entail an additional wire being connected to the monitor circuitry where in some instances it is desirable that the number of wires associated with the electrosurgical apparatus be reduced to a minimum. Accordingly, an activation control unit 59 may be employed which is responsive to the sensed shield current over line 63 or the sensed return current over line 67 to provide a battery power supply for the various circuits of monitor circuitry 25.
However, even with the use of the safety shield as disclosed in Newton et al., additional problems continue to exist when such an apparatus is used in a laparoscopic procedure or the like. Specifically, in order to facilitate sterilization and replacement of electrosurgical instruments, there is a demand for a shielded electrosurgical instrument that accepts a plurality of electrosurgical inserts (such as graspers, scissors, etc.) that can easily be removed and replaced. Furthermore, there is a need for such inserts to be reliably and securing attached to the shielded electrosurgical instrument in order to prevent undesirable loosening during a surgical procedure. However, it is still desirable for the electrosurgical insert to be easily removed to facilitate sterilization of the electrosurgical instrument.
Furthermore, potential problems exist with respect to the interconnection between an electrosurgical generator and a shielded electrosurgical instrument. Although precautions to ensure proper interconnection to the shield of the electrosurgical instrument have been previously taken, there still exists a possibility that a false signal indicating proper interconnection could result. In such case, a surgeon could proceed under the false impression that the shield monitor was operational when in fact it is not. Of course, in the event of an insulation failure, the results could be catastrophic.
Furthermore, the structure of the connectors used to make a connection between the active and shield electrodes of and electrosurgical instrument and an electrosurgical generator and monitor are such that foreign matter, such a liquids encountered during the surgical procedure, could invade the connector housing, thus creating an electrical short circuit between the active electrode and the shield electrode of the electrosurgical instrument. Again, such a situation is undesirable when performing an electrosurgical procedure.
Also, inserts designed for use with electrosurgical instruments are such that a mechanical failure could occur during an electrosurgical procedure, thus rendering the electrosurgical instrument inoperative. Again, should such failure occur during a surgical procedure, danger to the patient could result.
Furthermore, a need exists for an integral shield assembly adapted for use with a plurality of electrosurgical instruments such that the electrosurgical instruments can be selectively interconnected with, and positioned with respect to, the shield assembly. This allows separation of the shield assembly and electrosurgical instrument to be easily accomplished to facilitate sterilization of the instrument. Furthermore, replacement of defective or worn shield assemblies can be easily accomplished with the provision of a standardized shield assembly suitable for use with a plurality of electrosurgical instruments.
The present invention provides a solution to the above mentioned, and other, problems with prior electrosurgical apparatus and specifically with prior shielded electrosurgical apparatus. In accordance with the present invention, an electrosurgical instrument having a safety shield for use in laparoscopic or like electrosurgical procedures designed to receive a plurality of electrosurgical instrument inserts is disclosed. The electrosurgical inserts are designed so as to provide quick and easy attachment to the electrosurgical apparatus while still providing enhanced resistance to rotation forces encountered during an electrosurgical procedure, and to distribute actuation forces occurring during use. The safety shield includes a crimped portion for transferring forces that occur during operation of an articulating instrument inserted therein to a handle assembly of the electrosurgical instrument. The electrosurgical instrument has a seal that reduces or prevents electrical current from flowing between the active electrode and shield assemblies. The electrosurgical instrument further includes a connector assembly for receiving a mating cable connector and for providing a fail-safe interconnection that is sealed to prevent breakdown between a shield and active conductor of the instrument. A second preferred embodiment of the electrosurgical instrument is adapted to be removably connected with a replaceable shield/connector assembly through which an electrosurgical insert is inserted. Furthermore, positioning of the shield with respect to the electrosurgical insert can easily be accomplished.
In view of the forgoing, it is an object of the present invention to provide an insert for an electrosurgical apparatus having a novel structure that securely attaches the insert to the electrosurgical apparatus.
It is another object of the present invention to provide an insert for an electrosurgical apparatus having a novel structure that permits quick, easy and secure attachment of the insert to the electrosurgical apparatus.
It is a still further object of the present invention to provide an insert for an electrosurgical apparatus having a novel structure that allows for quick and easy replacement of the insert in the electrosurgical apparatus.
It is yet another object of the present invention to provide an insert for an electrosurgical apparatus having a novel structure that can be quickly and easily attached to the electrosurgical apparatus while still providing enhanced resistance to rotation forces encountered during an electrosurgical procedure.
It is a further object of the present invention to provide an insert for an electrosurgical apparatus having a novel interface with the electrosurgical apparatus to redistribute actuation forces applied on that insert during operation.
It is a further object of the present invention to provide an insert for an electrosurgical apparatus having a protrusion that is received by the electrosurgical apparatus and that is used to actuate the electrosurgical insert.
It is another object of the present invention to provide a shield assembly for an electrosurgical instrument that provides a secure interconnection between the shield and associated insulating layers, and the instrument handle assembly to permit actuation force to be more directly transferred to the handle assembly.
It is still another object of the present invention to provide a shield assembly for an electrosurgical instrument that includes a crimped portion for transferring forces that occur during operation of an articulating instrument inserted therein to a handle assembly of the electrosurgical instrument.
It is a further object of the present invention to provide a shielded electrosurgical instrument having improved electrical insulation between the active electrode and shield assemblies.
It is yet another object of the present invention to provide a shielded electrosurgical instrument having a seal that reduces or prevents electrical current from flowing between the active electrode and shield assemblies.
It is another object of the present invention to prevent surface breakdown from occurring between an active electrode and a shield of an electrosurgical instrument.
It is still another object of the present invention to provide an electrosurgical instrument having an improved connector assembly adapted to receive a connector for supplying electrosurgical active potential and for providing interconnection with the electrosurgical instrument shield. It is another object of the present invention to provide an electrosurgical instrument having an improved connector assembly designed to provide redundant contact points to a shield of the electrosurgical instrument in order to provide for fail-safe operation of that instrument.
It is yet another object of the present invention to provide a cord connector assembly for interconnecting to an electrosurgical instrument and constructed to provide a seal to prevent liquids and other foreign matter from entering the electrosurgical instrument during a surgical procedure.
It is a still further object of the present invention to provide an electrosurgical instrument comprising an integral shield assembly adapted for use with a plurality of electrosurgical instruments such that the electrosurgical instruments can be selectively interconnected with, and positioned with respect to, the shield assembly.
It is an object of the present invention to provide an electrosurgical instrument that includes an integral handle/articulatable instrument assembly that is inserted through an integral shield/connector assembly within the sterile field.
It is an object of the present invention to provide a shield assembly for use with an electrosurgical instrument that can be easily removed and replaced in the event of damage or wear to the shield assembly.
It is an object of the present invention to provide a standardized electrosurgical instrument having a plurality of articulating replaceable/disposable instruments thereon that is adapted for interconnection with a standard, replaceable and/or disposable shield assembly.
It is an object of the present invention to provide an electrosurgical instrument having position means integrally formed therewith to permit position of the electrosurgical instrument with respect to a electrosurgical shield assembly.